Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011
Increase (Decrease) in Accumulated Other Comprehensive Income
Balance, at the beginning of period				$ (94)
Current period change	(37)		(21)	(21)		(24)
Balance, at the end of period	(115)			(115)
Commodity contracts
Increase (Decrease) in Accumulated Other Comprehensive Income
Unrealized derivative gains (losses), after-tax recorded in accumulated other comprehensive income (loss)	12			12
Unrealized gains on cash flow hedges, net of tax, expected to be reclassified into earnings during the next 12 months				13
Interest rate contracts
Increase (Decrease) in Accumulated Other Comprehensive Income
Unrealized derivative gains (losses), after-tax recorded in accumulated other comprehensive income (loss)	(69)			(69)
Unrealized Losses on Cash Flow Hedges
Increase (Decrease) in Accumulated Other Comprehensive Income
Balance, at the beginning of period				(34)
Current period change				(23)
Balance, at the end of period	(57)			(57)
Unrecognized Losses and Prior Service Adjustments, Net
Increase (Decrease) in Accumulated Other Comprehensive Income
Balance, at the beginning of period				(60)	[1]
Current period change				2	[1]
Balance, at the end of period	$ (58)	[1]		$ (58)	[1]

[1] For further detail, see Note 8—Compensation and Benefit Plans.